// This file is part of Substrate.
//
// Copyright (C) 2020-2021 Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

//! A CLI extension for substrate node, adding sub-command to pretty print debug info
//! about blocks and extrinsics.
//!
//! The blocks and extrinsics can either be retrieved from the database (on-chain),
//! or a raw SCALE-encoding can be provided.

#![warn(missing_docs)]

pub mod cli;
pub mod command;

use codec::{Decode, Encode};
use sc_client_api::BlockBackend;
use sp_blockchain::HeaderBackend;
use sp_core::hexdisplay::HexDisplay;
use sp_runtime::{
    generic::BlockId,
    traits::{Block, Hash, HashFor, NumberFor},
};
use std::{fmt, fmt::Debug, marker::PhantomData, str::FromStr};

/// A helper type for a generic block input.
pub type BlockAddressFor<TBlock> = BlockAddress<<HashFor<TBlock> as Hash>::Output, NumberFor<TBlock>>;

/// A Pretty formatter implementation.
pub trait PrettyPrinter<TBlock: Block> {
    /// Nicely format block.
    fn fmt_block(&self, fmt: &mut fmt::Formatter, block: &TBlock) -> fmt::Result;
    /// Nicely format extrinsic.
    fn fmt_extrinsic(&self, fmt: &mut fmt::Formatter, extrinsic: &TBlock::Extrinsic) -> fmt::Result;
}

/// Default dummy debug printer.
#[derive(Default)]
pub struct DebugPrinter;
impl<TBlock: Block> PrettyPrinter<TBlock> for DebugPrinter {
    fn fmt_block(&self, fmt: &mut fmt::Formatter, block: &TBlock) -> fmt::Result {
        writeln!(fmt, "Header:")?;
        writeln!(fmt, "{:?}", block.header())?;
        writeln!(fmt, "Block bytes: {:?}", HexDisplay::from(&block.encode()))?;
        writeln!(fmt, "Extrinsics ({})", block.extrinsics().len())?;
        for (idx, ex) in block.extrinsics().iter().enumerate() {
            writeln!(fmt, "- {}:", idx)?;
            <DebugPrinter as PrettyPrinter<TBlock>>::fmt_extrinsic(self, fmt, ex)?;
        }
        Ok(())
    }

    fn fmt_extrinsic(&self, fmt: &mut fmt::Formatter, extrinsic: &TBlock::Extrinsic) -> fmt::Result {
        writeln!(fmt, " {:?}", extrinsic)?;
        writeln!(fmt, " Bytes: {:?}", HexDisplay::from(&extrinsic.encode()))?;
        Ok(())
    }
}

/// Aggregated error for `Inspector` operations.
#[derive(Debug, derive_more::From, derive_more::Display)]
pub enum Error {
    /// Could not decode Block or Extrinsic.
    Codec(codec::Error),
    /// Error accessing blockchain DB.
    Blockchain(sp_blockchain::Error),
    /// Given block has not been found.
    NotFound(String),
}

impl std::error::Error for Error {
    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
        match *self {
            Self::Codec(ref e) => Some(e),
            Self::Blockchain(ref e) => Some(e),
            Self::NotFound(_) => None,
        }
    }
}

/// A helper trait to access block headers and bodies.
pub trait ChainAccess<TBlock: Block>: HeaderBackend<TBlock> + BlockBackend<TBlock> {}

impl<T, TBlock> ChainAccess<TBlock> for T
where
    TBlock: Block,
    T: sp_blockchain::HeaderBackend<TBlock> + sc_client_api::BlockBackend<TBlock>,
{
}

/// Blockchain inspector.
pub struct Inspector<TBlock: Block, TPrinter: PrettyPrinter<TBlock> = DebugPrinter> {
    printer: TPrinter,
    chain: Box<dyn ChainAccess<TBlock>>,
    _block: PhantomData<TBlock>,
}

impl<TBlock: Block, TPrinter: PrettyPrinter<TBlock>> Inspector<TBlock, TPrinter> {
    /// Create new instance of the inspector with default printer.
    pub fn new(chain: impl ChainAccess<TBlock> + 'static) -> Self
    where
        TPrinter: Default,
    {
        Self::with_printer(chain, Default::default())
    }

    /// Customize pretty-printing of the data.
    pub fn with_printer(chain: impl ChainAccess<TBlock> + 'static, printer: TPrinter) -> Self {
        Inspector { chain: Box::new(chain) as _, printer, _block: Default::default() }
    }

    /// Get a pretty-printed block.
    pub fn block(&self, input: BlockAddressFor<TBlock>) -> Result<String, Error> {
        struct BlockPrinter<'a, A, B>(A, &'a B);
        impl<'a, A: Block, B: PrettyPrinter<A>> fmt::Display for BlockPrinter<'a, A, B> {
            fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
                self.1.fmt_block(fmt, &self.0)
            }
        }

        let block = self.get_block(input)?;
        Ok(format!("{}", BlockPrinter(block, &self.printer)))
    }

    fn get_block(&self, input: BlockAddressFor<TBlock>) -> Result<TBlock, Error> {
        Ok(match input {
            BlockAddress::Bytes(bytes) => TBlock::decode(&mut &*bytes)?,
            BlockAddress::Number(number) => {
                let id = BlockId::number(number);
                let not_found = format!("Could not find block {:?}", id);
                let body = self.chain.block_body(&id)?.ok_or_else(|| Error::NotFound(not_found.clone()))?;
                let header = self.chain.header(id)?.ok_or_else(|| Error::NotFound(not_found.clone()))?;
                TBlock::new(header, body)
            },
            BlockAddress::Hash(hash) => {
                let id = BlockId::hash(hash);
                let not_found = format!("Could not find block {:?}", id);
                let body = self.chain.block_body(&id)?.ok_or_else(|| Error::NotFound(not_found.clone()))?;
                let header = self.chain.header(id)?.ok_or_else(|| Error::NotFound(not_found.clone()))?;
                TBlock::new(header, body)
            },
        })
    }

    /// Get a pretty-printed extrinsic.
    pub fn extrinsic(
        &self,
        input: ExtrinsicAddress<<HashFor<TBlock> as Hash>::Output, NumberFor<TBlock>>,
    ) -> Result<String, Error> {
        struct ExtrinsicPrinter<'a, A: Block, B>(A::Extrinsic, &'a B);
        impl<'a, A: Block, B: PrettyPrinter<A>> fmt::Display for ExtrinsicPrinter<'a, A, B> {
            fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
                self.1.fmt_extrinsic(fmt, &self.0)
            }
        }

        let ext = match input {
            ExtrinsicAddress::Block(block, index) => {
                let block = self.get_block(block)?;
                block.extrinsics().get(index).cloned().ok_or_else(|| {
                    Error::NotFound(format!("Could not find extrinsic {} in block {:?}", index, block))
                })?
            },
            ExtrinsicAddress::Bytes(bytes) => TBlock::Extrinsic::decode(&mut &*bytes)?,
        };

        Ok(format!("{}", ExtrinsicPrinter(ext, &self.printer)))
    }
}

/// A block to retrieve.
#[derive(Debug, Clone, PartialEq)]
pub enum BlockAddress<Hash, Number> {
    /// Get block by hash.
    Hash(Hash),
    /// Get block by number.
    Number(Number),
    /// Raw SCALE-encoded bytes.
    Bytes(Vec<u8>),
}

impl<Hash: FromStr, Number: FromStr> FromStr for BlockAddress<Hash, Number> {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        // try to parse hash first
        if let Ok(hash) = s.parse() {
            return Ok(Self::Hash(hash));
        }

        // then number
        if let Ok(number) = s.parse() {
            return Ok(Self::Number(number));
        }

        // then assume it's bytes (hex-encoded)
        sp_core::bytes::from_hex(s).map(Self::Bytes).map_err(|e| {
            format!("Given string does not look like hash or number. It could not be parsed as bytes either: {}", e)
        })
    }
}

/// An extrinsic address to decode and print out.
#[derive(Debug, Clone, PartialEq)]
pub enum ExtrinsicAddress<Hash, Number> {
    /// Extrinsic as part of existing block.
    Block(BlockAddress<Hash, Number>, usize),
    /// Raw SCALE-encoded extrinsic bytes.
    Bytes(Vec<u8>),
}

impl<Hash: FromStr + Debug, Number: FromStr + Debug> FromStr for ExtrinsicAddress<Hash, Number> {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        // first try raw bytes
        if let Ok(bytes) = sp_core::bytes::from_hex(s).map(Self::Bytes) {
            return Ok(bytes);
        }

        // split by a bunch of different characters
        let mut it = s.split(|c| c == '.' || c == ':' || c == ' ');
        let block = it.next().expect("First element of split iterator is never empty; qed").parse()?;

        let index = it
            .next()
            .ok_or_else(|| format!("Extrinsic index missing: example \"5:0\""))?
            .parse()
            .map_err(|e| format!("Invalid index format: {}", e))?;

        Ok(Self::Block(block, index))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use sp_core::hash::H160 as Hash;

    #[test]
    fn should_parse_block_strings() {
        type BlockAddress = super::BlockAddress<Hash, u64>;

        let b0 = BlockAddress::from_str("3BfC20f0B9aFcAcE800D73D2191166FF16540258");
        let b1 = BlockAddress::from_str("1234");
        let b2 = BlockAddress::from_str("0");
        let b3 = BlockAddress::from_str("0x0012345f");

        assert_eq!(b0, Ok(BlockAddress::Hash("3BfC20f0B9aFcAcE800D73D2191166FF16540258".parse().unwrap())));
        assert_eq!(b1, Ok(BlockAddress::Number(1234)));
        assert_eq!(b2, Ok(BlockAddress::Number(0)));
        assert_eq!(b3, Ok(BlockAddress::Bytes(vec![0, 0x12, 0x34, 0x5f])));
    }

    #[test]
    fn should_parse_extrinsic_address() {
        type BlockAddress = super::BlockAddress<Hash, u64>;
        type ExtrinsicAddress = super::ExtrinsicAddress<Hash, u64>;

        let e0 = ExtrinsicAddress::from_str("1234");
        let b0 = ExtrinsicAddress::from_str("3BfC20f0B9aFcAcE800D73D2191166FF16540258:5");
        let b1 = ExtrinsicAddress::from_str("1234:0");
        let b2 = ExtrinsicAddress::from_str("0 0");
        let b3 = ExtrinsicAddress::from_str("0x0012345f");

        assert_eq!(e0, Err("Extrinsic index missing: example \"5:0\"".into()));
        assert_eq!(
            b0,
            Ok(ExtrinsicAddress::Block(
                BlockAddress::Hash("3BfC20f0B9aFcAcE800D73D2191166FF16540258".parse().unwrap()),
                5
            ))
        );
        assert_eq!(b1, Ok(ExtrinsicAddress::Block(BlockAddress::Number(1234), 0)));
        assert_eq!(b2, Ok(ExtrinsicAddress::Block(BlockAddress::Number(0), 0)));
        assert_eq!(b3, Ok(ExtrinsicAddress::Bytes(vec![0, 0x12, 0x34, 0x5f])));
    }
}
